Britain's top government and security officials are meeting again Saturday to discuss the fatal poisoning of a former Russian spy by a radioactive material.

The meeting of Britain's elite emergency committee known as COBRA is in response to Thursday's death of Alexander Litvinenko. British authorities say the 43-year- old ex-KGB agent was killed by a heavy dose of a rare radioactive substance, polonium-210.

London police are retracing Litvinenko's movements from November first, the day he became ill.

In a deathbed statement, he accused Russian President Vladimir Putin of ordering his murder, a charge Moscow denies.

The British government has formally asked Russia for any information it has that would aid the investigation into Litvinenko's death. He became a British citizen last month after defecting from Russia six years ago.

On Friday, Britain's Health Protection Agency said Litvinenko would have had to have eaten or inhaled the polonium-210, or been given a dose through a wound to be made sick by the substance.

Traces of polonium-210 have been found at Litvinenko's home and at a restaurant and a London hotel where the former spy met contacts the day he became ill.

One contact, Italian academic Mario Scarmella, says he told Litvinenko they both were on an assassination list.

The contact said the list was drawn up by those responsible for the October murder of Russian journalist Anna Politkovskaya, who was a frequent critic of the Kremlin and its policies in the separatist republic of Chechnya.